Restore SEBPatch

SafeExamBrowser.UserInterface.Shared/Activators/TaskViewKeyboardActivator.cs

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+/*
+ * Copyright (c) 2024 ETH Zürich, IT Services
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System.Windows.Input;
+using SafeExamBrowser.Logging.Contracts;
+using SafeExamBrowser.UserInterface.Contracts.Shell;
+using SafeExamBrowser.UserInterface.Contracts.Shell.Events;
+using SafeExamBrowser.WindowsApi.Contracts;
+using SafeExamBrowser.WindowsApi.Contracts.Events;
+
+namespace SafeExamBrowser.UserInterface.Shared.Activators
+{
+	public class TaskviewKeyboardActivator : KeyboardActivator, ITaskviewActivator
+	{
+		private bool Activated, LeftShift, Tab;
+		private ILogger logger;
+
+		public event ActivatorEventHandler Deactivated;
+		public event ActivatorEventHandler NextActivated;
+		public event ActivatorEventHandler PreviousActivated;
+
+		public TaskviewKeyboardActivator(ILogger logger, INativeMethods nativeMethods) : base(nativeMethods)
+		{
+			this.logger = logger;
+		}
+
+		protected override void OnBeforePause()
+		{
+			if (Activated)
+			{
+				logger.Debug("Auto-deactivation.");
+				Deactivated?.Invoke();
+			}
+
+			Activated = false;
+		}
+
+		protected override void OnBeforeResume()
+		{
+			Activated = false;
+			LeftShift = false;
+			Tab = false;
+		}
+
+		protected override bool Process(Key key, KeyModifier modifier, KeyState state)
+		{
+			/*
+			if (IsDeactivation(modifier))
+			{
+				return false;
+			}
+
+			if (IsActivation(key, modifier, state))
+			{
+				return true;
+			}
+			*/
+
+			return false;
+		}
+
+		private bool IsActivation(Key key, KeyModifier modifier, KeyState state)
+		{
+			var changed = false;
+			var pressed = state == KeyState.Pressed && modifier.HasFlag(KeyModifier.Alt);
+
+			switch (key)
+			{
+				case Key.Tab:
+					changed = Tab != pressed;
+					Tab = pressed;
+					break;
+				case Key.LeftShift:
+					changed = LeftShift != pressed;
+					LeftShift = pressed;
+					break;
+			}
+
+			var isActivation = Tab && changed;
+
+			if (isActivation)
+			{
+				Activated = true;
+
+				if (LeftShift)
+				{
+					logger.Debug("Detected sequence for previous instance.");
+					PreviousActivated?.Invoke();
+				}
+				else
+				{
+					logger.Debug("Detected sequence for next instance.");
+					NextActivated?.Invoke();
+				}
+			}
+
+			return isActivation;
+		}
+
+		private bool IsDeactivation(KeyModifier modifier)
+		{
+			var isDeactivation = Activated && !modifier.HasFlag(KeyModifier.Alt);
+
+			if (isDeactivation)
+			{
+				Activated = false;
+				LeftShift = false;
+				Tab = false;
+
+				logger.Debug("Detected deactivation sequence.");
+				Deactivated?.Invoke();
+			}
+
+			return isDeactivation;
+		}
+	}
+}